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DataServiceQuery<TElement>.AddQueryOption Method

Creates a new DataServiceQuery<TElement> with the query option set in the URI generated by the returned query.

Namespace:  System.Data.Services.Client
Assembly:  Microsoft.Data.Services.Client (in Microsoft.Data.Services.Client.dll)
public DataServiceQuery<TElement> AddQueryOption(
	string name,
	Object value
)

Parameters

name
Type: System.String
The string value that contains the name of the query string option to add.
value
Type: System.Object
The object that contains the value of the query string option.

Return Value

Type: System.Data.Services.Client.DataServiceQuery<TElement>
A new query that includes the requested query option appended to the URI of the supplied query

The query options are added to the resultant URI using ?name=value&name2=value2… syntax where the name maps directly to the name parameter and the value is obtained by calling ToString on the value parameter. The name starts with $.

Non-WCF Data Services syntax does not start with $. Non-WCF Data Services query options can be added using this method. It is legal to add the same query option twice if the option is not an WCF Data Services query option. If a query option is added that is already present in the underlying URI, an exception is thrown.

The $select query option cannot be added to a query URI by using the AddQueryOption(String, Object) method. We recommend that you use the LINQ Select<TSource, TResult>(IEnumerable<TSource>, Func<TSource, TResult>) method and have the client generate the $select query option in the request URI.

The following example shows a DataServiceQuery<TElement> that is used with sequential AddQueryOption method calls to only return orders with a freight cost of more than $30 and to order the results by the ship date in descending order.

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);

// Define a query for orders with a Freight value greater than 30
// and that is ordered by the ship date, descending.
DataServiceQuery<Order> selectedOrders = context.Orders
    .AddQueryOption("$filter", "Freight gt 30")
    .AddQueryOption("$orderby", "OrderID desc");

try
{
    // Enumerate over the results of the query.
    foreach (Order order in selectedOrders)
    {
        Console.WriteLine("Order ID: {0} - Ship Date: {1} - Freight: {2}", 
            order.OrderID, order.ShippedDate, order.Freight);
    }
}
catch (DataServiceQueryException ex)
{
    throw new ApplicationException(
        "An error occurred during query execution.", ex);
}

The following example shows how to compose a LINQ query that is equivalent to the previous query that used AddQueryOption.

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);

// Define a query for orders with a Freight value greater than 30
// and that is ordered by the ship date, descending.
var selectedOrders = from o in context.Orders
                     where o.Freight > 30
                     orderby o.ShippedDate descending 
                     select o;

try
{
    // Enumerate over the results of the query.
    foreach (Order order in selectedOrders)
    {
        Console.WriteLine("Order ID: {0} - Ship Date: {1} - Freight: {2}",
            order.OrderID, order.ShippedDate, order.Freight);
    }
}
catch (DataServiceQueryException ex)
{
    throw new ApplicationException(
        "An error occurred during query execution.", ex);
}
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